The overall goals of this ACE renewal application will be to further develop our interdisciplinary basic and clinical research program at Columbia primarily focused on the evaluation of novel therapeutic approaches to human autoimmune diseases including systemic lupus erythematosus (SLE), rheumatoid and psoriatic arthritis (RA), multiple sclerosis (MS), type I diabetes mellitus (TIDM), biliary cirrhosis and scleroderma. In each of these diseases, there are ongoing basic and clinical research programs involving pathophysiologic and/or clinical immunotherapeutic studies. We hypothesize that there are four principal events involved in the immunopathogenesis of these diseases: (1) predisposing genes establish a T-cell repertoire capable of recognizing self peptides intrinsic to the autoimmune process; (2) previously tolerant autoreactive T-cell clones are activated, expand to change the T cell repertoire to reflect autoreactive effector T cells and migrate to sites of inflammation; (3) regulatory mechanisms, including cytokines and CD4+ and CD8+ regulatory T cells fail and (4) pathogenic autoantibodies and T cells effect tissue injury. We predict that reducing the clonal expansion and migration of relevant autoreactive T cells by blockade of TCR signaling with agents like anti-CD3 or interruption of the signaling and migration of autoreactive memory T cells with agents like anti-VLA-1 could down-modulate disease activity. We propose to test these hypotheses during the natural history of disease and during specific immune intervention. In this ACE renewal, we plan to continue ongoing studies of anti-CD3 therapy of TIDM, initiate trials of biliary cirrhosis employing Mycophenolate Mofetil and continue pre-clinical assessment of the VLA-1 pathway as a prelude to clinical trials with anti-VLA-1 moAbs anticipated to begin in 2004. During these studies, we will: (1) identify by PCR based CDR3 length techniques and TCR sequencing, autoantigen-driven expansions in the CD4 and CD8 cz_ TCR repertoire; (2) Identify changes in the T cell functional response to autoantigens and (3) directly study the regulatory interactions of TH1, TH2 as well as CD4+ and CD8+ T cells in controlling the TCR repertoire. In select patients, we will directly study cells at the site of inflammation (CNS, skin, kidney, joints) using HVS immortalization techniques as well as by laser capture technology for repertoire and microarray analysis of activated genes. In addition, we plan new basic studies of the control of the autoreactive T cell repertoire in autoimmune disease by analysis of EAE in the mouse and studies of human regulatory cells in TIDM.